Carboxylic acid alkyl amides are well-known intermediates for the manufacture of polymers. Fatty acid alkanolamides, which form a sub-group of this species, are also applied as foam boosters in detergents, while particularly amides, which are based on dimethyl amine and medium chain fatty acids, are used as environmentally friendly, so-called “green” solvents, particularly in agriculture.
Usually, carboxylic acid alkyl amides are obtained from the reaction of triglycerides, carboxylic acids, their esters or acyl halides with alkyl or alkanol amines (see, for example, U.S. Pat. No. 5,388,644). Acyl halides, particularly chlorides, however are difficult to handle, highly corrosive and toxic. In case of esters or triglycerides, alcohols or glycerol are obtained as an unwanted by-product which needs to be separated off and therefore makes the process expensive. The reaction between carboxylic acids and amines usually takes place in the gas phase, which makes it necessary to use closed reactors and high pressure. Due to salt formation, an excess of amine is necessary to achieve an acceptable conversion. Therefore, either non-reacted amine has to be removed after the amidation has been completed, which has a negative impact on the manufacturing costs, or a certain level of free amine in the product has to be accepted which is not always possible, especially in cases where the amides are used as environmentally friendly solvents.